We determined the safety, feasibility, and efficacy of a treatment regimen consisting of maxillary sinus aspiration and irrigation with or without adenoidectomy, followed by culture-directed intravenous antibiotics and oral prophylaxis, for children with chronic rhinosinusitis refractory to oral antimicrobial therapy. Twenty-seven children (age 1-12 years, mean 6.7 years) with symptomatic (mean duration 16 months) and computed tomography- proven sinus disease, which persisted despite at least 1 month of oral antibiotics, were treated. Twenty-four patients (89%) had complete resolution of their presenting symptoms after intravenous therapy; in 3 (11%), intravenous therapy failed and endoscopic sinus surgery was required. Follow- up data were available for 26 of the children (96%); 23 of them had initial complete resolution. At last follow-up (mean 282 days, range 26-1095 days), 10 of these 23 patients (44%.) remained asymptomatic, and 13 (57%) had had at least one other episode of sinusitis (mean 1.0, range 1-3) treated with oral antibiotics, with resolution. Treatment-related complications included superficial thrombophlebitis (7%), diarrhea (7%), intravenous catheter guide- wire kink requiring yenatomy (4%), and serum sickness-like syndrome (4%). These preliminary results suggest that this treatment plan is relatively safe and feasible and that it may be a reasonable alternative to endoscopic sinus surgery in children with chronic rhinosinusitis unresponsive to orally administered antimicrobial therapy.